This invention relates to an electromechanical clutch for an engine cooling fan.
Experience has conclusively demonstrated that operation of the engine cooling fan is necessary only during a relatively small percentage of the time that a vehicle engine is operated. If the fan is driven when it is not necessary, the power used to rotate the fan is wasted, thereby increasing gasoline consumption. Accordingly, it is desirable to provide a clutch which engages the fan to rotate with the vehicle engine when the cooling effect of the fan is needed but which disengages the fan when its cooling effect is not needed. Such a fan clutch is disclosed in prior U.S. Pat. Application Ser. No. 900,829, filed Apr. 28, 1978 now U.S. Pat. No. 4,217,976, and in pending U.S. Pat. Application Ser. No. 951,103, filed Oct. 13, 1978. Both of these applications disclose an electromechanical clutch which includes a flexible band member that provides the driving connection between the driven and driving members of the clutch.
The present invention is an improvement over the clutches disclosed in these prior applications, and permits better wrapping of the band about the driving member to give the clutch a higher torque capacity.